6 research outputs found
Low ML-Decoding Complexity, Large Coding Gain, Full-Rate, Full-Diversity STBCs for 2 X 2 and 4 X 2 MIMO Systems
This paper (Part of the content of this manuscript has been accepted for
presentation in IEEE Globecom 2008, to be held in New Orleans) deals with low
maximum likelihood (ML) decoding complexity, full-rate and full-diversity
space-time block codes (STBCs), which also offer large coding gain, for the 2
transmit antenna, 2 receive antenna () and the 4 transmit antenna, 2
receive antenna () MIMO systems. Presently, the best known STBC for
the system is the Golden code and that for the system is
the DjABBA code. Following the approach by Biglieri, Hong and Viterbo, a new
STBC is presented in this paper for the system. This code matches
the Golden code in performance and ML-decoding complexity for square QAM
constellations while it has lower ML-decoding complexity with the same
performance for non-rectangular QAM constellations. This code is also shown to
be \emph{information-lossless} and \emph{diversity-multiplexing gain} (DMG)
tradeoff optimal. This design procedure is then extended to the
system and a code, which outperforms the DjABBA code for QAM constellations
with lower ML-decoding complexity, is presented. So far, the Golden code has
been reported to have an ML-decoding complexity of the order of for
square QAM of size . In this paper, a scheme that reduces its ML-decoding
complexity to is presented.Comment: 28 pages, 5 figures, 3 tables, submitted to IEEE Journal of Selected
Topics in Signal Processin
Full Diversity Space-Time Block Codes with Low-Complexity Partial Interference Cancellation Group Decoding
Partial interference cancellation (PIC) group decoding proposed by Guo and
Xia is an attractive low-complexity alternative to the optimal processing for
multiple-input multiple-output (MIMO) wireless communications. It can well deal
with the tradeoff among rate, diversity and complexity of space-time block
codes (STBC). In this paper, a systematic design of full-diversity STBC with
low-complexity PIC group decoding is proposed. The proposed code design is
featured as a group-orthogonal STBC by replacing every element of an Alamouti
code matrix with an elementary matrix composed of multiple diagonal layers of
coded symbols. With the PIC group decoding and a particular grouping scheme,
the proposed STBC can achieve full diversity, a rate of and a
low-complexity decoding for transmit antennas. Simulation results show that
the proposed codes can achieve the full diversity with PIC group decoding while
requiring half decoding complexity of the existing codes.Comment: 10 pages, 3 figures
Generalized Silver Codes
For an transmit, receive antenna system (
system), a {\it{full-rate}} space time block code (STBC) transmits complex symbols per channel use. The well known Golden code is an
example of a full-rate, full-diversity STBC for 2 transmit antennas. Its
ML-decoding complexity is of the order of for square -QAM. The
Silver code for 2 transmit antennas has all the desirable properties of the
Golden code except its coding gain, but offers lower ML-decoding complexity of
the order of . Importantly, the slight loss in coding gain is negligible
compared to the advantage it offers in terms of lowering the ML-decoding
complexity. For higher number of transmit antennas, the best known codes are
the Perfect codes, which are full-rate, full-diversity, information lossless
codes (for ) but have a high ML-decoding complexity of the order
of (for , the punctured Perfect codes are
considered). In this paper, a scheme to obtain full-rate STBCs for
transmit antennas and any with reduced ML-decoding complexity of the
order of , is presented. The codes constructed are
also information lossless for , like the Perfect codes and allow
higher mutual information than the comparable punctured Perfect codes for . These codes are referred to as the {\it generalized Silver codes},
since they enjoy the same desirable properties as the comparable Perfect codes
(except possibly the coding gain) with lower ML-decoding complexity, analogous
to the Silver-Golden codes for 2 transmit antennas. Simulation results of the
symbol error rates for 4 and 8 transmit antennas show that the generalized
Silver codes match the punctured Perfect codes in error performance while
offering lower ML-decoding complexity.Comment: Accepted for publication in the IEEE Transactions on Information
Theory. This revised version has 30 pages, 7 figures and Section III has been
completely revise
Spatial diversity in MIMO communication systems with distributed or co-located antennas
The use of multiple antennas in wireless communication systems has gained much attention during the last decade. It was shown that such multiple-input multiple-output (MIMO) systems offer huge advantages over single-antenna systems. Typically, quite restrictive assumptions are made concerning the spacing of the individual antenna elements. On the one hand, it is typically assumed that the antenna elements at transmitter and receiver are co-located, i.e., they belong to some sort of antenna array. On the other hand, it is often assumed that the antenna spacings are sufficiently large, so as to justify the assumption of independent fading. In this thesis, the above assumptions are relaxed. In the first part, it is shown that MIMO systems with distributed antennas and MIMO systems with co-located antennas can be treated in a single, unifying framework. In the second part this fact is utilized, in order to develop appropriate transmit power allocation strategies for co-located and distributed MIMO systems. Finally, the third part focuses on specific synchronization problems that are of interest for distributed MIMO systems